1. Field of the Invention
The present invention relates to a method for manufacturing a monolithic ceramic part such as a monolithic capacitor, and a cutting device used for cutting an unfired ceramic laminate when manufacturing the monolithic ceramic part.
2. Description of the Related Art
In order to manufacture a monolithic ceramic electronic part such as monolithic capacitor, first a mother ceramic laminate composed of stacked mother ceramic green sheets and including inner electrodes is obtained. Next, as shown in FIG. 12, the mother laminate 51 is cut with a cutting blade 52 into individual ceramic laminates of monolithic capacitor units. Typically a thin cutting blade 52 with a thickness of about 0.05 mm to 0.3 mm is used in order to cut the mother ceramic laminate 51 with a high degree of accuracy.
The cutting blade 52 is held by a holder 53, and the holder 53 is coupled to a driving source (not shown). After cutting, the mother ceramic laminate 51 is moved in direction A (marked with an arrow in FIG. 12), or the holder is moved in direction B (also marked with the arrow in the figure), and the mother ceramic laminate 52 is cut at next portion thereof. Then, the mother ceramic laminate 51 is rotated 90, and the mother ceramic laminate 51 is cut in a like manner, in a direction orthogonal to the direction in which it was previously cut.
Thereafter, individual ceramic laminates of monolithic capacitor units thus obtained are fired to obtain ceramic sintered bodies. By providing outer electrodes to opposite end faces of each of the sintered bodies, monolithic capacitors are obtained.
In order to achieve size-reduction in the monolithic capacitor electronic parts, the thickness of each ceramic layer sandwiched between inner electrodes must be decreased with the result that the number of inner electrode layers must be increased. Also, a size-reduction in planar dimensions of footprint of the monolithic capacitor is desired to enhance the surface mounting density of a circuit board, which results in the increasing in the overall thickness of the ceramic laminate.
When trying to cut a ceramic laminate of which the number of laminated inner electrode layers is increased, or of which thickness is increased, the cutting blade 52 is inevitably subjected to high cutting resistance.
As a result, although a high speed cutting is needed in order to increase productivity, an increased speed does not permit the stable cutting of the mother ceramic laminate 51 in the direction orthogonal to the principal plane 51a thereof.
Also, since the cutting blade 52 is thin, once cutting resistance grows, the cutting blade 52 can be bent as it moves across the mother ceramic laminate 51, as shown in FIG. 13, even though the cutting blade 52 enters the mother ceramic laminate 51 in the direction orthogonal to the principal plane 51a thereof. As a result, the cut face obtained by cutting the ceramic laminate can be tilted, and in an extreme case, inner electrodes 54 will be undesirably exposed.
This has constituted a problem not only in the monolithic ceramic electronic part, but also in the other monolithic ceramic parts that are obtained by laying up a plurality of ceramic green sheets and firing them. That is, since the resistance to the cutting blade increases with the number of laminated sheets, stable cutting of the mother ceramic laminate cannot be achieved at an increased speed.
Accordingly, it is an object of the present invention to provide a manufacturing method for a monolithic ceramic part, having the step of speedily and stably cutting a ceramic laminate even if the number of laminations is increased, and provide a cutting device for a ceramic laminate used in the above-mentioned manufacturing method.
The manufacturing method for a monolithic ceramic part in accordance with the present invention comprises preparing an unfired mother ceramic laminate; dividing the mother ceramic laminate into individual laminates of monolithic ceramic part units by cutting the mother ceramic laminate with a cutting blade extending through guides disposed on opposite sides of the cutting blade and being located in the vicinity of one planar principal surface of the mother ceramic laminate to control the cutting direction of the blade; and firing individual ceramic laminates obtained by the cutting operation.
Preferably, cutting is performed while keeping the above-mentioned guides abutted against the one principal plane of the mother ceramic laminate.
In accordance with one aspect of the present invention, the cutting blade is detached from the ceramic laminate after cutting while keeping the guides abutted against the planar principal surface of the mother ceramic laminate.
In accordance with another aspect of the present invention, cutting is performed with a clearance provided between the guides and the cutting blade.
In accordance with still another aspect of the present invention, the guides each have tilted guide faces tilted relative to the sides of the cutting blade, and thereby the cutting direction is tilted from a direction orthogonal to the planar principal surface of the mother ceramic laminate.
The cutting device for use in a ceramic laminate in accordance with the present invention is a cutting device for cutting a ceramic laminate, comprising: a cutting blade; a drive connected to the cutting blade so as to move the cutting blade in a thickness direction of the ceramic laminate in order to cut said ceramic laminate in the thickness direction thereof; and guides disposed on opposite sides of the cutting blade in the vicinity of the ceramic laminate in order to control the direction that the cutting blade enters the ceramic laminate.
In one aspect of the cutting device for use in a ceramic laminate in accordance with the present invention, there are further provided first actuators, each connected to a respective guide, in order to move at least one of said guides toward said cutting blade. A single actuator connected to one of the guides can also be used.
In another aspect of the cutting device for use in a ceramic laminate in accordance with the present invention, there is further provided a base member having a lower surface on which the cutting blade is fixed, and which can be moved in the upper and lower directions by the drive; and second actuators which are coupled to the lower surface of the base member, and which are each connected to the guides so as to move the guides in the upper and lower directions independently of the base member.
In still another aspect of the cutting device for use in a ceramic laminate in accordance with the present invention, the guides each have guide faces for controlling the cutting direction of the cutting blade, and the guide faces are each formed to be tilted relative to the thickness direction of the ceramic laminate in order to cut the ceramic laminate in the direction intersecting the thickness direction of the ceramic laminate.